THE GREAT EARTHAQUKE OF S. E. JAPAN 161 



toi)ogTai)hical cliange occurred : first, a vast depression extending from 

 the centra] Y^ri of iSaganii Bay to Oosinia, and second, an elevation 

 extending over the bottom of that part of the bay lying to the north- 

 east of the depressed part. Evidently this was the seat of origin of 

 the last great commotion ; the distribution of seismic intensity and of 

 tidal waves as well as the position of the seisniic focus deduced from 

 instrumental observations all support this view. Possibly a very 

 remarkable fault may have been produced along the belt which divides 

 the depressed and the elevated areas, but so far it has not been 

 discovered. 



17. Fault lines. Prof. Yamasaki, among others, has made ela- 

 borate investigations of fault lines. His description of the topograph- 

 ical changes in the sea-botton/'^ is very instructive and would 

 convince every reader of his paper of the possibility of the main fault 

 line just alluded to. Further, his description goes on to mention 

 several faults of a secondary nature as follows : — 



1. Sitaura Fault, which took place in the Miura Peninsula, 

 almost crossing it in the direction ]SI70°W, and with its 

 maximum vertical dislocation as much as 1.5 m. 



2. Arakawa Fault, which took place to the west of Yoko- 

 hama and whose direction, total extension and maximum 

 vertical dislocation are respectively ^25°^^, 1 km. and 

 1 m. 



3. Hatusima Fault, which crosses an islet of that name 

 near the N. E. coast of the Idu Peninsula and whose direc- 

 tion, total extension and maximum vertical dislocation 

 are respectively N30°W, 1 km. and 1 m. in all. 



4. Group of faults crossing the central part of Awa Province 

 approximately in the east-westerly direction, namely, 

 Enmeizi Fault (total extention = 3 km., max. vertical 

 dislocation = l m.) ; Uto Fault (total extension = 0.7 km., 

 max. vertical dislocation = 1 m.) ; and Takigawa Fault 

 (total extension = 2.5 km., max. vertical dislocation 

 = 1 m.). (PL XLIII.) 



18. Tmtmni, or tidal waves. Tunami in the strict scientific 

 meaning of the term were observed not only on the Pacific coast of 



6) Eeports (in Japanese) of tlie Imp. Eartliq. Tnv. Conim., No. 100, B. 



